Electronic writing and erasing pencil

ABSTRACT

An electronic writing instrument for rewritable electronic writing surfaces. A self-powered, untethered, pencil-like instrument uses a perpendicular fringe field for changing the orientation of pixels composed of bistable, bichromal colorant elements. An appendix hereto describes bistable, bichromal, molecular colorant.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] Not Applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not Applicable.

REFERENCE TO AN APPENDIX

[0003] The present application includes a hard copy appendix comprisingpertinent specification pages and drawings of co-inventors' U.S. patentapplication Ser. No. 09/844,862, filed Apr. 27, 2001, by ZHANG, WILLIAMSand VINCENT for MOLECULAR MECHANICAL DEVICES WITH A BAND GAP CHANGEACTIVATED BY AN ELECTRIC FIELD FOR OPTICAL SWITCHING APPLICATIONS asrelates to subject matter claimed in accordance with the presentinvention.

BACKGROUND OF THE INVENTION

[0004] 1. Field of the Invention

[0005] The present invention relates generally to an electronic writingand erasing device, and specifically to a handheld, pencil-like,electronic writing and erasing instrument adapted for use with arewritable media, displays, and surfaces, particularly those using ananotechnology-based display colorant.

[0006] 2. Description of Related Art

[0007] There have been recent developments in the field of “electronicmedia.” Commercially available mechanisms by Xerox Corporation withrespect to its Gyricon™ sphere technology and E Ink Corporation withrespect to its bichromal microcapsule technology are used to produceelectronic images, improving resolution over conventional displays suchas liquid crystal displays (“LCD”). See e.g., U.S. Pat. No. 5,604,027(Sheridon, assignee Xerox Corp.) and U.S. Pat. No. 6,124,851 (Jacobson,assignee E Ink Corp.).

[0008] Assignee herein, Hewlett-Packard Company, has gone beyond thesemicrocapsule-based colorant technologies by creating a bi-modalmolecular colorant that is useful for rewritable media, displays,surfaces, and the like. In some embodiments, the molecules are alsobistable, meaning that an electronic holding field is not necessary tomaintain a particular state. The term “rewritable” as used herein shouldbe understood to mean writable and erasable. In the main, the goal ofsuch electronic, rewritable product development is to provide a meansfor producing electronic images that truly resembles hard copy inappearance and readability. The Appendix hereto provides a detaileddescription of one of the Hewlett-Packard inventions in this field oftechnology.

[0009] In general, electronic display and electronic media devices useconventional input mechanisms such as computer keyboards, computeradapted styli, computer mouse, Wacomm cable-connected Deskpad andwriting stylus, and the like, coupled to electrode arrays proximate theelectronic media, or electronic media based display, to image data intoa readable format.

[0010] There is a need for a computer-free device to manually image andto annotate images produced electronically.

BRIEF SUMMARY OF THE INVENTION

[0011] In its basic aspect, the present invention provides an electronicstylus apparatus including: a portable power source; connected to thepower source, at least one electrode for producing a localized,emanating, electric field wherein the field is of a strength sufficientto reorient electronic picture elements formed of an electricallybistable colorant.

[0012] In another aspect, the present invention provides a method forelectronic erasable writing, the method including: providing a surfacehaving picture elements defined by a bistable, bichromal, colorantelements; and moving a portable, perpendicular electrical fringe field,tuned to changing orientation of the colorant elements, across saidsurface in a manner substantially identical to conventional handwriting.

[0013] In still another aspect, the present invention provides anerasable writing system including: an electronically writable-erasablesurface having a layer of bistable, bichromal, colorant thereon; and aportable, electronic stylus adapted for writing and erasing saidcolorant.

[0014] The foregoing summary and list of advantages is not intended bythe inventors to be an inclusive list of all the aspects, objects,advantages and features of the present invention nor should anylimitation on the scope of the invention be implied therefrom. ThisSummary is provided in accordance with the mandate of 37 C.F.R. 1.73 andM.P.E.P. 608.01(d) merely to apprise the public, and more especiallythose interested in the particular art to which the invention relates,of the nature of the invention in order to be of assistance in aidingready understanding of the patent in future searches. Other objects,features and advantages of the present invention will become apparentupon consideration of the following explanation and the accompanyingdrawings, in which like reference designations represent like featuresthroughout the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In accordance with 37 C.F.R. 1.84(u), in order to preventconfusion with FIGURES of the Appendix hereto, the drawings of thisapplication use double capital letter suffices.

[0016]FIG. 1AA is a schematic drawing in elevation view of a writinginstrument according to the present invention, demonstrating anelectrical writing field vector, “E1.”

[0017]FIG. 1BB is a schematic drawing in elevation view of the writinginstrument of FIG. 1AA, demonstrating an electrical erasing writingfield vector, “E2”.

[0018]FIG. 1CC is an electrical schematic drawing for the presentinvention as shown in FIGS. 1AA and 1BB.

[0019] FIGS. 2AA, 2BB, and 2CC are schematic drawings in transparentelevation view of the present invention as shown in FIGS. 1AA, 1BB and1CC, demonstrating writing features and methodology.

[0020] FIGS. 3AA, 3BB, and 3CC are schematic drawings in transparentelevation view of the present invention as shown in FIGS. 1AA, 1BB, 1CC,2AA, 2BB, and 2CC, demonstrating erasing features and methodology.

[0021]FIG. 4AA is an electrical schematic diagram associated with thepresent invention as shown in FIGS. 2AA, 2BB, 2CC, 3AA, 3BB and 3CC.

[0022]FIG. 5AA is an illustration of the present invention in anelectronic writing system embodiment.

[0023] The drawings referred to in this specification should beunderstood as not being drawn to scale except if specifically annotated.

DETAILED DESCRIPTION OF THE INVENTION

[0024] Reference is made now in detail to a specific embodiment of thepresent invention, which illustrates the best mode presentlycontemplated by the inventors for practicing the invention. Alternativeembodiments are also briefly described as applicable.

[0025] Definitions

[0026] The following terms and ideas are applicable to both the presentdiscussion and the Appendix hereto.

[0027] The term “self-assembled” as used herein refers to a system thatnaturally adopts some geometric pattern because of the identity of thecomponents of the system; the system achieves at least a local minimumin its energy by adopting this configuration.

[0028] The term “singly configurable” means that a switch can change itsstate only once via an irreversible process such as an oxidation orreduction reaction; such a switch can be the basis of a programmableread-only memory (PROM), for example.

[0029] The term “reconfigurable” means that a switch can change itsstate multiple times via a reversible process such as an oxidation orreduction; in other words, the switch can be opened and closed multipletimes, such as the memory bits in a random access memory (RAM) or acolor pixel in a display.

[0030] The term “bistable” as applied to a molecule means a moleculehaving two relatively low energy states (local minima) separated by anenergy (or activation) barrier. The molecule may be either irreversiblyswitched from one state to the other (singly configurable) or reversiblyswitched from one state to the other (reconfigurable). The term“multi-stable” refers to a molecule with more than two such low energystates, or local minima.

[0031] The term “bi-modal” for colorant molecules in accordance with thepresent invention may be designed to include the case of no, or low,activation barrier for fast but volatile switching. In this lattersituation, bistability is not required, and the molecule is switchedinto one state by the electric field and relaxes back into its originalstate upon removal of the field; such molecules are referred to as“bi-modal”. In effect, these forms of the bimodal colorant molecules are“self-erasing”. In contrast, in bistable colorant molecules the colorantmolecule remains latched in its state upon removal of the field(non-volatile switch), and the presence of the activation barrier inthat case requires application of an opposite field to switch themolecule back to its previous state. Also, “molecular colorant” as usedhereinafter as one term to describe aspects of the present invention isto be distinguished from other chemical formulations, such as dyes,which act on a molecular level; in other words, “molecular colorant”used hereinafter signifies that the colorant molecules as described inthe Appendix and their equivalents are employed in accordance with thepresent invention.

[0032] Micron-scale dimensions refers to dimensions that range from 1micrometer to a few micrometers in size.

[0033] Sub-micron scale dimensions refers to dimensions that range from1 micrometer down to 0.05 micrometers.

[0034] Nanometer scale dimensions refers to dimensions that range from0.1 nanometers to 50 nanometers (0.05 micrometers).

[0035] Micron-scale and submicron-scale wires refers to rod orribbon-shaped conductors or semiconductors with widths or diametershaving the dimensions of 0.05 to 10 micrometers, heights that can rangefrom a few tens of nanometers to a micrometer, and lengths of severalmicrometers and longer.

[0036] “HOMO” is the common chemical acronym for “highest occupiedmolecular orbital”, while “LUMO” is the common chemical acronym for“lowest unoccupied molecular orbital”. HOMOs and LUMOs are responsiblefor electronic conduction in molecules and the energy difference betweenthe HOMO and LUMO and other energetically nearby molecular orbitals isresponsible for the color of the molecule.

[0037] An “optical switch,” in the context of the present invention,involves changes in the electromagnetic properties of the molecules,both within and outside that detectable by the human eye, e.g., rangingfrom the far infra-red (IR) to deep ultraviolet (UV). Optical switchingincludes changes in properties such as absorption, reflection,refraction, diffraction, and diffuse scattering of electromagneticradiation.

[0038] The term “transparency” is defined within the visible spectrum tomean that optically, light passing through the colorant is not impededor altered except in the region in which the colorant spectrallyabsorbs. For example, if the molecular colorant does not absorb in thevisible spectrum, then the colorant will appear to have water cleartransparency.

[0039] The term “omni-ambient illumination viewability” is definedherein as the viewability under any ambient illumination condition towhich the eye is responsive.

[0040] As a general proposition, “media” in the context of the presentinvention includes any surface, whether portable or fixed, that containsor is layered with a molecular colorant or a coating containingmolecular colorant in accordance with the present invention wherein“bistable” molecules are employed; for example, both a flexible sheetexhibiting all the characteristics of a piece of paper and a writablesurface of an appliance (be it a refrigerator door or a computingappliance using the molecular colorant). “Display” (or “screen”) in thecontext of the present invention includes any apparatus that employs“bimodal” molecules, but not necessarily bistable molecules. Because ofthe blurred line regarding where media type devices ends and displaymechanisms begin, no limitation on the scope of the invention isintended nor should be implied from a designation of any particularembodiment as a “media” or as a “display.”

[0041] As will become apparent from reading the Detailed Description andAppendix, “molecule” can be interpreted in accordance with the presentinvention to mean a solitary molecular device, e.g., an optical switch,or, depending on the context, may be a vast array of molecular-leveldevices, e.g., an array of individually addressable, pixel-sized,optical switches, which are in fact linked covalently as a singlemolecule in a self-assembling implementation. Thus, it can be recognizedthat some molecular systems comprise a super-molecule where selectivedomain changes of individual molecular devices forming the system areavailable. The term “molecular system” as used herein refers to bothsolitary molecular devices used systematically, such as in a regulararray pixel pattern, and molecularly linked individual devices. Nolimitation on the scope of the invention is intended by interchangeablyusing these terms nor should any be implied.

[0042] Shown schematically in FIGS. 1AA and 1BB is an electronic writingand erasing instrument, or “e-pencil” hereinafter, 100 in accordancewith the present invention. A barrel, or casing, 101 is formed in ashape and dimension suitable to handheld usage and may have the shapeand feel of a conventional pencil. It includes a write tip 103 and erasehead 105 that function on electronic rewritable surfaces just like aconventional pencil on conventional paper. It can optionally be providedwith a clip 107 for convenient pocket or other holder carrying.

[0043] The write tip 103 provides a first polarity directed electricfield (E,) source. The erase head 105 provides an opposite polaritydirected electric field (E₂) source. Optionally, switching mechanism(not shown) may be provided wherein the polarity at either of the pencilends may be reversed such that the same end can provide the write orerase function or wherein both may be reversed to change the nib sizefor the function of interest, e.g., narrow erase to broad erase; seee.g., FIG. 4M description hereinafter.

[0044] To describe at least one implementation of a molecular colorantused to create a rewritable surface upon which the present invention canbe used, the reader is directed to the Appendix hereto. Moreover, thepresent invention will be useful with other electronically rewritablesurfaces such as those made using Gyricon or E-Ink products.

[0045] Referring now also to FIGS. 2AA through 2CC, the write tip 103 isused to create at least one picture-element (pixel) sized point ormulti-pixel line in contact and translation across a rewritable surface.The preferred embodiment of the e-pencil 100 is an untethered, handheld,battery-powered device. Batteries are depicted as two, exemplary, commonAAA-sized batteries 201, 201′ connected in series in a known manner. Itwill be recognized by those skilled in the art that other power packmechanisms, such as AC-transformers can be used to power the e-pencil100, providing the ability for greater or lesser power than a batterydriven implementation. Moreover, field strength maintaining and surgeprotection mechanisms as would be known in the art may be employed withthe present invention.

[0046] An electrical schematic is shown in FIG. 4AA for a simplifiedembodiment where one tip electrode 403 is used for both writing anderasing. The batteries 201, 201′ are represented as power source “V.”The power source V is connected via a double pole, double throw switch401 (shown in an OFF position) to the tip electrode 403 (analogous toFIGS. 1AA, 1BB, elements 103 and 105 combined). The dashed-line arrow405 represents the capability of switching the polarity of the voltageto the tip electrode 403.

[0047] In a more elaborate embodiment, as shown in FIGS. 2AA through3CC, it may be desirable to have a writing tip 103 configured as anelectrical point source and an erasing head 105 configured as a broaderelectrical area source just as a conventional pencil does.

[0048] Returning to FIGS. 2AA through 2CC and now also FIGS. 3AA through3CC, one embodiment of the e-pencil 100 has the electric field write tip101 and the electric field erase head 105 appropriately connected in aknown manner to a battery, or batteries, 201, 201′. The write tip 101preferably includes a circular rod 107′ and cylinder 107″ electrode pairthat are concentric and closely spaced. The write tip 103 is ideallyhoused within a conical end cap of the e-pencil 100, giving theappearance of a standard lead pencil. The electrode pair 107′, 107″ iselectrically biased (±V as in FIG. 4AA) to produce a fringefield—represented in FIGS. 2CC and 3CC as semi-circular lines labeled“Perpendicular Fringe Field” (PFF)—having a principal field vector 203that emanates along the axis of the e-pencil 100 from the central rodelectrode 107′, and substantially perpendicular to an erasable writingsubstrate 205, returning to the cylinder electrode 107″. The writingsubstrate 205 has a layer 202 of colorant composed of bistable colorantpixels (see Appendix). The electrodes 107′, 107″ are biased so theprincipal field vector 203 from the write tip 101 orients, or otherwiseswitches, bistable colorant 202 (see Appendix) pixels exposed to the PFFto its writing image color.

[0049] Note that the drawn line width of the image produced by thewriting tip 103 is dependent on the electrode geometry and may be variedwith the bias voltage. The written lines may be “tunable,” i.e,broadened in width by increasing the voltage (+V−) on the writingelectrode 107. For example, a hand controlled switch 109—e.g., apotentiometer added to FIG. 4M between the power source V and electrode403 accessible along the barrel 101 of the pencil 100 may be used forthis purpose. The writing tip 103 itself may be interchangeable withother line source nib embodiments to simulate fine writing instrumentssuch as fountain pens. Vector 203′ represents a higher voltage,“broader” nib effect. More sophisticated, known manner, voltage controlcircuitry may be employed.

[0050] Only the principal field vector 203 writes the image. The fieldreturn lines are radially distributed between the rod and cylinderelectrodes 107′, 107″, thereby diluting field intensity below thewriting threshold. The writing tip electrodes 107′, 107″ may be madefrom most any conductive metal and may be further coated or plated toproduce a good wear and low friction writing surface. The writing tip103 may be gimbaled to allow correct contact and orientation of thewriting tip with the media surface 202 while the e-pencil is held at anangle to the media surface.

[0051] The erase head 105 consists of an electrode pair 105′, 105″ withgeometry suitable for producing a PFF having a more distributedprincipal field area. By comparison to the writing tip 103, the erasehead 105 may consist of a larger area circular rod and cylinderelectrode. Alternative geometries, such as a cross-shaped centerelectrode and conformal outer electrode as shown in FIG. 3BB can bedesigned to suit a particular implementation. The erase head electrodegeometries are selected in these examples to mimic the approximate erasearea of a standard lead pencil, but others may be employed. The erasehead electrodes 105′, 105″ are biased to produce a principal field areaor lines that orient, or otherwise switch, bistable colorant pixelscontacted by the field to its transparent or media background color inthe media area in contact with the erase head 105.

[0052] The writing tip's conical end cap and erase head are preferablyassembled, e.g. threaded, at opposing ends of the barrel 101 that formsthe casing for the e-pencil 100. This allows the batteries 201, 201′used to power the e-pencil to be contained and electrically connectedwithin the barrel in a manner similar to a standard flashlight; inalternative embodiments (not shown) button-type or other commerciallyavailable batteries may be employed.

[0053] Standard step-up or step-down voltage components and circuitrymay be added to drive the electrodes at voltages greater than or lessthan that provided by the batteries. Conventional electrical switch orswitches (not shown) operable on the cylinder exterior may be used toactivate the e-pencil, change writing or erasing line widths, or changethe function of either the writing tip or erase head to its opposingfunction. In the latter case, the erase head may be biased to writebroad lines for such things as area fills.

[0054] The electronic pencil and rewritable paper combination offergreat benefit over a wide set of applications. The electronic pencil isnearly as simple in construction as a common flashlight and should havelow manufacturing cost. The pencil uses very low current fields to writeand erase and, therefore, should be very battery efficient. Standardnote pads, such as Post-It™ Notes, used for reminders, to-do lists,grocery lists, phone messages and the like, may be substituted for by amore permanent, less messy, single rewritable sheet used in combinationwith the e-pencil. Such a sheet, for example, may have a magneticbacking for attachment to a refrigerator, cabinet or interior carsurface. The electronic erase feature eliminates the mess and residualimage (stain) that often accompany similarly intended pencil and paperor white board and highlighting pen products; the electronic erasefunction provides a completely renewed writing surface.

[0055] In operation, to write on a surface having a pixel surfaceincluding a layer 202 of field-orientable, bistable, colorant (note thatthis can be any surface or media type upon which the colorant layer canbe formed), the end-user moves the e-pencil 100 across the surface inthe same manner as writing with a conventional pencil or pen. Theperpendicular fringe field E1 (see FIGS. 1AA and 2CC) re-orients thepixels in the colorant layer, matching the strokes of the e-pencil 100.To erase writing produced in that manner, the end-user uses the reversefringe field E2 (see FIGS. 1BB and 3CC), moving the “eraser” in the samemanner as erasing with a conventional pencil or pen.

[0056] An exemplary embodiment writing system 500 in accordance with thepresent invention is shown in FIG. 5AA. An electronic folio 501 includesa writing board, or similar support platform, 503 and, optionally, asecurity cover 505. An electronic media 507 having a writing surfaceincluding a bistable, bichromal colorant (such as formed of a layer ofmolecular devices as described in the Appendix hereto) is supported bythe board 503. The end-user writes and erases to the electronic media507 using the untethered, electronic stylus 100 described hereinbefore.

[0057] The foregoing description of the preferred embodiment of thepresent invention has been presented for purposes of illustration anddescription. It is not intended to be exhaustive or to limit theinvention to the precise form or to exemplary embodiments disclosed.Obviously, many modifications and variations will be apparent topractitioners skilled in this art. Similarly, any process stepsdescribed might be interchangeable with other steps in order to achievethe same result. The embodiment was chosen and described in order tobest explain the principles of the invention and its best mode practicalapplication, thereby to enable others skilled in the art to understandthe invention for various embodiments and with various modifications asare suited to the particular use or implementation contemplated. It isintended that the scope of the invention be defined by the claimsappended hereto and their equivalents. Reference to an element in thesingular is not intended to mean “one and only one” unless explicitly sostated, but rather means “one or more.” Moreover, no element, component,nor method step in the present disclosure is intended to be dedicated tothe public regardless of whether the element, component, or method stepis explicitly recited in the following claims. No claim element hereinis to be construed under the provisions of 35 U.S.C. Sec. 112, sixthparagraph, unless the element is expressly recited using the phrase“means for . . . ” and no process step herein is to be construed underthose provisions unless the step or steps are expressly recited usingthe phrase “comprising the step(s) of . . . ”

What is claimed is:
 1. An electronic stylus apparatus comprising: aportable power source; connected to the power source, at least oneelectrode for producing a localized, eminating, electric field whereinthe field is of a strength sufficient to reorient electronic pictureelements formed of an electrically bistable colorant.
 2. The apparatusas set forth in claim 1 comprising: connected between said power sourceand said electrode electronic circuitry for switching the polarity ofsaid electric field.
 3. The apparatus as set forth in claim 1comprising: connected between said power source and said electrodeelectronic circuitry for selectively varying the intensity of saidelectric field.
 4. The apparatus as set forth in claim 1 comprising:said at least one electrode is adapted for writing and erasingelectrically bistable, bichromal, molecular colorant.
 5. The apparatusas set forth in claim 1 comprising: a hand-held cylindrical pencilshaped body wherein said power source and electrode are incorporatedtherein such that said apparatus is used in the manner of a conventionalwriting instrument.
 6. The apparatus as set forth in claim 1 comprising:electronic circuitry for maintaining a substantially constant electronicfield output of the apparatus.
 7. A method for electronic erasablewriting, the method comprising: providing a surface having pictureelements defined by a bistable, bichromal, colorant elements; and movinga portable, perpendicular electrical fringe field, tuned to changingorientation of the colorant elements, across said surface in a mannersubstantially identical to conventional handwriting.
 8. The method asset forth in claim 7 comprising: providing a writing-erasing instrumentfor producing said perpendicular fringe field such that said field islocalized to eminating from a tip of said instrument.
 9. The method asset forth in claim 7 comprising: switching polarity of saidperpendicular fringe field from a first polarity for writing operationsto a second polarity for erasing operations.
 10. The method as set forthin claim 7 wherein the strength of the perpendicular fringe field istunable such that the marking pixel width and erasing pixel width ofsaid tip is adjustable.
 11. The method as set forth in claim 7 whereinproviding said surface includes using bistable, bichromal, molecularcolorant.
 12. An erasable writing system comprising: an electronicallywritable-erasable surface having a layer of bistable, bichromal,colorant thereon; and a poratable, electronic stylus adapted for writingand erasing said colorant.
 13. The system as set forth in claim 12, saidcolorant comprising: a molecular system, said system includingelectrochromic, switchable molecules, each of said molecules beingselectively switchable between at least two optically distinguishablestates, wherein said system is distributable on the substrate therebyforming an erasably writable surface.
 14. The system as set forth inclaim 13 comprising: said molecules exhibit an electric field inducedband gap change.
 15. The system as set forth in claim 14 comprising:said electric field induced band gap change occurs via a mechanismselected from a group including (1) molecular conformation change or anisomerization, (2) change of extended conjugation via chemical bondingchange to change the band gap, and (3) molecular folding or stretching.